Abstract: An additive manufacturing method includes dividing a three-dimensional model shape into a plurality of layers, and dividing each divided layer into a plurality of bead models. A trapezoidal bead model has four vertices. The dividing into the plurality of bead models includes, in the same layer, the bead model for a previously formed weld bead and the bead model for a subsequently formed weld bead that is adjacent to the previously formed weld bead are arranged to have an overlapping portion, and among four vertices of the bead model for the subsequently formed weld bead, selecting as a selected vertex the vertex positioned at an end of the bottom line of the bead model, the end being away from the overlapping portion, and rotating the other three vertices about the selected vertex to change a shape of the trapezoidal bead model.

Abstract: A target shape is set from a three-dimensional shape data of an additively-manufactured object, and the set target shape is sliced into a plurality of bead models having shapes corresponding to weld beads. A dripping amount of a filler metal to a lower layer during bead formation in a bead deposition portion where the sliced bead models overlap vertically is predicted according to welding conditions of the weld beads. A bead height of each bead model in the bead deposition portion is modified according to the predicted dripping amount. A deposition plan to manufacture the additively-manufactured object is created by using the plurality of bead models including the bead model with modified bead height.